Study on the Structure of Peroxide Cross-Linked Polyethylene Pipes with Several Stabilizers


Cross-linked polyethylene (PEX) pipes used in hot water supply are required for high mechanical strength and high creep resistance at high temperature. Especially PEX-a pipes which are made by peroxide cross-linking have better performance, such as creep resistance and thermal shock resistance than the pipes made by the other cross-linking method. Because the PEX-a pipes indicate the higher cross-link degree as compared with the other PEX pipes. In this study, the PEX-a pipes which were mixed with several stabilizers were tested to evaluate the effects on cross-link degree and the oxygen induction time. And also they are evaluated with the chlorine aqueous solution by the performance of the long-term hydrostatic pressure test and the long-term hydro dynamic pressure test. As a result, it was found that the combination of antioxidants for PEX-a pipes plays an important role to prolong the oxygen induction time without inhibiting the cross-linking. From the results of the 1H pulsed NMR measurement over the melting point of polyethylene, it was found that each peroxide PEX pipe with different antioxidant combinations indicated the different proportion and crosslink density of cross-linked region, in addition, that these pipes had the effective structure of cross-linking for the hydrostatic and hydrodynamic pressure test with the chlorine aqueous solution. Therefore, it was considered to be useful results for studies of the stricture of cross-linking of polyethylene.

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H. Hirabayashi, A. Iguchi, K. Yamada, H. Nishimura, K. Ikawa and H. Honma, "Study on the Structure of Peroxide Cross-Linked Polyethylene Pipes with Several Stabilizers," Materials Sciences and Applications, Vol. 4 No. 9, 2013, pp. 497-503. doi: 10.4236/msa.2013.49060.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] C. Munier, E. Gaillard-Devaux, A. Tcharkhtchi and J. Verdu, “Durability of Cross-Linked Polyethylene Pipes under Pressure,” Journal of Materials Science, Vol. 37, No. 19, 2002, pp. 4159-4163. doi:10.1023/A:1020091920606
[2] B. Fayolle and J. Verdu, “EWF Method to Study Long Term Fracture Properties of Cross-Linked Polyethylene”, Polymer Engineering & Science, Vol. 45, No. 3, 2005, pp. 424-431. doi:10.1002/pen.20241
[3] Ghasemi and J. Morshedian, “The Effect of Co-Agent on the Peroxide Crosslinking of LDPE,” Iranian Polymer Journal, Vol. 12, No. 2, 2003, pp. 119-125.
[4] J. Barzin, H. Azizi and J. Morshedian, “Preparation of Silane-Grafted and Moisture Crosslinked Low Density Polyethylene. Part II: Electrical, Thermal and Mechanical Properties,” Polymer-Plastics Technology and Engineering, Vol. 46, No. 3, 2007, pp. 305-310. doi:10.1080/03602550601155815
[5] J. Morshedian and P. M. Hoseinpour, “Polyethylene CrossLinking by Two-Step Silane Method: A Review,” Iranian Polymer Journal, Vol. 18, No. 2, 2009, pp. 103-128.
[6] R. Ayyer, A. Hiltner and E. Baer, “A Fatigue-to-Creep Correlation in Air for Application to Environmental Stress Cracking of Polyethylene,” Journal of Materials Science, Vol. 42, No. 16, 2007, pp. 7004-7015. doi:10.1007/s10853-006-1108-2
[7] M. Parsons, E. V. Stepanov, A. Hiltner and E. Baer, “Correlation of Fatigue and Creep Slow Crack Growth in a Medium Density Polyethylene Pipe Material,” Journal of Materials Science, Vol. 35, No. 11, 2000, pp. 2659-2674. doi:10.1023/A:1004789522642
[8] M. Parsons, E. V. Stepanov, A. Hiltner and E. Baer, “Effect of Strain Rate on Stepwise Fatigue and Creep Slow Crack Growth in High Density Polyethylene,” Journal of Materials Science, Vol. 35, No. 8, 2000, pp. 1857-1866. doi:10.1023/A:1004741713514
[9] J. Weon, “Effects of Thermal Ageing on Mechanical and Thermal Behaviors of Linear Low Density Polyethylene Pipe,” Polymer Degradation and Stability, Vol. 95, No. 1, 2010, pp. 14-20. doi:10.1016/j.polymdegradstab.2009.10.016
[10] J. Viebke and U. W. Gedde, “Assessment of Lifetime of Hot-Water Polyethylene Pipes Based on Oxidation Induction Time Data,” Polymer Engineering & Science, Vol. 38, No. 8, 1998, pp. 1244-1250. doi:10.1002/pen.10293
[11] X. Colin, L. Audouin, J. Verdu, M. R.Evesque, B. Rabaud, F. Martin and F. Bourgine, “Aging of Polyethylene pipes Transporting Drinking Water Disinfected by Chlorine Dioxide. Part II—Lifetime Prediction,” Polymer Engineering & Science, Vol. 49, No. 8, 2009, pp. 1642-1652. doi:10.1002/pen.21387
[12] Basell Polyolefins, “Technical Manual-Materials Used in Pipe Extrusion,” 2005.
[13] A. Whelton, A. Dietrich and D. Gallagher, “Contaminant Diffusion, Solubility, and Material Property Differences between HDPE and PEX Potable Water Pipes,” Journal of Environmental Engineering, Vol. 136, No. 2, 2010, pp. 227-237. doi:10.1061/(ASCE)EE.1943-7870.0000147
[14] T. Nishi, “Physical Chemistry of Crosslinking,” Journal of The Society of Rubber Industry, Japan, Vol. 75, No. 2, 2002, pp. 48-54. doi:10.2324/gomu.75.48
[15] H. Iwabuki, K. Nagaya, T. Noguchi and E. Yamada, “Studies on Structures and Dynamic Properties of Peroxide-Crosslinked EPDM, Part 1. Network Structures in Peroxide-Crosslinked EPDM Examined by Dynamic Mechanical Analysis and Pulsed NMR,” Journal of The Society of Rubber Industry, Japan, Vol. 75, No. 9, 2002, pp. 409-414. doi:10.2324/gomu.75.409
[16] D. E. Duvall and D. B. Edwards, “Field Failure Mechanisms in HDPE Potable Water Pipe,” SPE-ANTEC Technical Papers, No. 57, 2011, pp. 1436-1441.

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